Some satellites provide relay service for transmission of television programs from a source to various user locations, as for example from network facilities in New York to the midwest and to the west coast of the US, so that local television broadcasters can simultaneously transmit the same program over large portions of the continental US. In such systems, there is a single user who uses a dedicated portion of a channel. The bandwidth allocated to that user is not used by other services or users. Thus, there is no need to schedule among users, because the single user has exclusive use of a given portion of the satellite resources.
In satellite, cable, or wireless network communications systems in which diverse services are offered to many users, a problem arises in the allocation of the available network resources among the various users. For example, in the Internet, there is always competition among the users, which can result in reduced service for all users. In satellite, cable and wireless networks intended for specific services, including internet access, the system operator may desire to provide some users of the system with preferential service. For example, in satellite television relaying services, there might be a given number of transponders, and some users might contract for the right to “bump” other users off their allocated transponders if the preferred user's transponder failed.
In wireless cell-phone services different factors are at work, because multiple users at various times demand and relinquish access to the available network resources, and the network must allocate the available resources among those users currently using the system or demanding access thereto. Ideally, each new user demanding access could be accommodated immediately. However, it is uneconomical to provide sufficient resources so that all users can access the network simultaneously. Efficiency requires that sufficient resources be available to provide satisfactory service most of the time, with the understanding that under unusual circumstances, or occasionally, some potential users will be unable to access the system. In cell phones networks, the allocation of system resources is immediate. That is, when a user demands cell-phone service, the network responds immediately, if resources are available, as for example with one audio channel. When resources are not available, the user is advised to wait and try again.
In the case of satellite, cable and wireless communications providing multiple service classes to a large number of users, additional problems of allocation arise.